If you think this is the end of capitalism, then buy gold, ammo, and toilet paper. But if you think this is fear-based panic selling, then stocks are on sale. When to buy? No one knows. We dollar cost average on the way up, and we should dollar cost average on the way down. Waiting for the bottom to buy assumes you will be good at calling the bottom, when you just did such a lousy job of calling the top.
When will it bounce back? My crystal ball doesn't show a bounce. There is a real problem behind this panic. Societal response to Covid-19 is harming the economy. Schools, parades, conferences, parties are canceling in an economy that requires consumer spending and continual Federal Reserve coddling just to keep it pointed in the right direction. I suspect that we will all get this flu, and we will heal and get back to normal by summer. I don't imagine the economy will recover as quickly as our species will, and I suspect we will be looking at how panic brought down the economy for much longer.